1. Field of the Invention
The present invention relates to a bending device for use in an automatic bender for relatively thin metal tubes having diameters less than about 20 mm, which tubes are frequently used in motor vehicles, various machinery, and other equipment such as oil or air supply conduits.
2. Description of the Prior Arts
A conventional bending device of this kind has a torsion unit that holds a pipe in an appropriate position. The pipe is rotated about its axis by the torsion unit to select the direction in which the pipe is to be bent. One or two bending units are provided on one or both sides of the torsion unit to bend the pipe in the selected direction.
In this conventional bending device, the pipe is rotated about its axis by the torsion unit. Therefore, when the pipe is bent in a stepwise fashion from its front end, the portion already bent on the side of the front end is twisted back and forth. Accordingly, if the pipe has a thin wall and is long, then the region at which the pipe is bent is severely deformed. For this reason, this bending device tends to be used to process only those pipes which are relatively large in diameter, have thick walls, and are short. For this reason, the conventional bending device has found only limited use.